1. Technical Field
The present invention relates to a physical quantity sensor, a pressure sensor, an altimeter, an electronic apparatus and a moving object.
2. Related Art
Pressure sensors including a diaphragm which is bent and deformed due to pressure reception are widely used. As such a pressure sensor, a sensor is known in which a piezoresistive element is disposed on a diaphragm, and which detects a pressure applied to the diaphragm by detecting the bending of the diaphragm using a sensor element (see, for example, JP-A-2006-3099).
The pressure sensor disclosed in JP-A-2006-3099 includes an SOI (Silicon On Insulator) substrate having a diaphragm formed therein, and four piezoresistive elements are provided on the diaphragm. These four piezoresistive elements are electrically connected to each other so as to constitute a Wheatstone bridge circuit. A pressure which is applied to the diaphragm is detected on the basis of an output of the Wheatstone bridge circuit.
However, in the pressure sensor disclosed in JP-A-2006-3099, since a pressure is detected using only the outputs of the piezoresistive elements which are provided in a single diaphragm, there is a problem that a S/Na signal to noise (S/N) ratio decreases with a reduction in size. This results from the following reason. That is, a reduction in the size of the diaphragm gives rise to a reduction in the area of a portion which is distorted by the pressure reception of the diaphragm, and sensitivity (signal) is reduced even when the area of the piezoresistive element is increased. When the area of the piezoresistive element is also reduced in conformity with the portion which is distorted by the pressure reception of the diaphragm, 1/f noise increases.